A great article on Vintage Computing on the causes of yellowing plastic on old computers. What I like is that he doesn't just stop with the first answer he is told but digs into more opinions and more reasons as to the cause. Yes it is a little old but I still appreciated the work by the author Benji Edwards.

So I may try Retrobrite (or is it Retr0bite, I always forget to spell with numbers) on my one-of-a-kind prototypes and if anything I think they were a tad more susceptible. Being paranoid I will try it on one of the more buggered up systems.

Now with all of that said I just found my personal C128D prototype from my office back in '85 and in part because it was put away and especially since the keyboard was snapped into the carrying niche, the system has very little yellow.

It does however have written on it in 27 years ago in Sharpie "Not an Amiga" since there was a rash of theft by the unknowing, or were in such a hurry that they would swipe anything that looked like an Amiga. I will post pictures in an upcoming artical, but essentually this is a system that proives that the goal had been to sell the C128D from day one, in fact our real goal for the dual processor, 128k/MMU based system with three OS's and a ([painful) rendition opf simultaneous 80 column and 40 column display was that if you bought one you didnt have then buy a Floppy Drive (courtesy of Greg Berlin and Dave Siracusa), it was a slef contained computer for casual intents and purposes.